Casement

Casement windows are hinged at the sides. Hinged windows such as casements generally have lower air leakage rates than sliding windows from the same manufacturer because the sash closes by pressing against the frame. Casement windows project outward, providing significantly better ventilation than sliders of equal size. Because the sash protrudes from the plane of the wall, it can be controlled to catch passing breezes, but screens must be placed on the interior side. Virtually the entire casement window area can be opened, while sliders are limited to less than half of the window area.

Single and Double Hung

In double-hung units, both sashes slide vertically. Only the bottom sash slides upward in a single-hung window. Ventilation area can vary from a small crack to an opening of one-half the total glass area. Screens can be placed on the exterior or interior of the window unit. Sliding windows, such as single- or double-hung units generally have higher air leakage rates than projecting or hinged windows.

Slider

Both sashes slide horizontally in a double-sliding window. Only one sash slides in a single-sliding window. Ventilation area can vary from a small crack to an opening of one-half the total glass area. Screens can be placed on the exterior or interior of the window unit. Horizontally sliding windows generally have higher air leakage rates than projecting or hinged windows.

Awning

Awning windows are hinged at the top and open outward. Hinged windows such as awnings generally have lower air leakage rates than sliding windows from the same manufacturer because the sash closes by pressing against the frame. Screens are placed on the interior of the window unit. Similar to casements, the entire window area can be opened, while sliders are limited to less than half of the window area.

Hopper

Hopper windows are hinged at the bottom and open inward. Hinged windows such as hoppers generally have lower air leakage rates than sliding windows from the same manufacturer because the sash closes by pressing against the frame. Screens are placed on the exterior of the window unit. Similar to casements, the entire window area can be opened, while sliders are limited to less than half of the window area.

Typical fixed or vented skylights include flat insulated glass units
with coatings and tints as well as domed profiles with single or double
layers of clear, tinted or diffusing plastic.

Window Sash Operation

When you select a window, there are numerous operating types to consider. Traditional operable window types include the projected or hinged types such as casement, awning, and hopper, and the sliding types such as double- and single-hung and horizontal sliding.

In addition, the window market includes fixed windows, storm windows, sliding and swinging patio doors, skylights and roof windows, and window systems that can be added to a house to create bay or bow windows, miniature greenhouses, or full sun rooms.

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